Demagnetization control for transmission actuator

ABSTRACT

A transmission actuator for a vehicle includes a housing, a first rocker for engaging a toothed wheel, a second rocker for rotating the first rocker to engage the toothed wheel, an engagement rod for rotating the second rocker, a solenoid arranged to displace the engagement rod, and a solenoid control circuit. The solenoid includes an iron core, a wire coil wrapped around the iron core, and a ferromagnetic plunger. The plunger is arranged to linearly displace in a first direction when a first directional current is applied to the wire coil, and linearly displace in a second direction when a second directional current is applied to the wire coil. The solenoid control circuit is arranged supply the first directional current when energized by a power source, and supply a decaying alternating current that includes the first directional current and the second directional current when the solenoid control circuit is de-energized.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation-in-part of U.S. application Ser. No.16/897,838, filed Jun. 10, 2020, which is a divisional of U.S.application Ser. No. 16/142,011, filed Sep. 26, 2018, and also claimsthe benefit of U.S. Provisional Application No. 63/309,320 filed Feb.11, 2022, each of which is incorporated by reference herein in itsentirety.

TECHNICAL FIELD

The present disclosure relates generally to a transmission actuator, andmore specifically to a demagnetization control for a transmissionactuator.

BACKGROUND

For known electromagnetic devices, windings in or around ferromagneticmaterial are energized to create magnet fields used to displacecomponents of the electromagnetic device. For example: a winding (coil)of a solenoid is energized to create a magnetic field displacing a pinsurrounded by the winding; and for a reluctance motor, circumferentiallydisposed windings of a stator are energized and de-energized in sequenceto create rotating magnetic fields that rotate a rotor for the pump.When windings are de-energized, residual magnetism remains in theferromagnetic material associated with the windings. The residualmagnetism resists displacement of the components to desired positions,for example, the pin for the solenoid returning to a pre-energizedposition, or continued rotation of the rotor for the pump.

SUMMARY

Example embodiments broadly comprise a transmission actuator for avehicle, including a fixed actuator housing, a first rocker, rotatablein the fixed actuator housing, for engaging a toothed wheel to preventrotation of the toothed wheel and a rotatable transmission component, asecond rocker, rotatable in the fixed actuator housing, for rotating thefirst rocker to engage the toothed wheel, an engagement rod, linearlydisplaceable within the fixed actuator housing, for rotating the secondrocker, a solenoid arranged to displace the engagement rod, and asolenoid control circuit. The solenoid includes an iron core, a wirecoil wrapped around the iron core, and a ferromagnetic plunger disposedradially inside the wire coil. The wire coil has a resistance and aninductance, and the ferromagnetic plunger is arranged to linearlydisplace in a first direction when a first directional current isapplied to the wire coil, and arranged to linearly displace in a seconddirection, opposite the first direction, when a second directionalcurrent, opposite the first directional current, is applied to the wirecoil. The solenoid control circuit is arranged supply the firstdirectional current when the solenoid control circuit is energized by apower source, and supply a decaying alternating current that includesthe first directional current and the second directional current whenthe solenoid control circuit is de-energized from the power source.

In an example embodiment, the transmission actuator has a lost motionspring disposed in a force path between the engagement rod and theferromagnetic plunger. In an example embodiment, the wire coil ismagnetized when the solenoid control circuit is energized by the powersource, and de-magnetized when the solenoid control circuit isde-energized from the power source. In some example embodiments, thesolenoid control circuit includes a capacitor connected to opposite endsof the wire coil. In an example embodiment, the solenoid control circuitis a passive control circuit. In some example embodiments, the solenoidcontrol circuit includes an H-bridge circuit and a controller thatcontrols a direction of a power source current from the power source. Inan example embodiment, the solenoid control circuit is an active controlcircuit.

Other example embodiments broadly comprise a method of controlling thetransmission actuator including applying the first directional currentwith the solenoid control circuit to magnetize the wire coil, charge thecapacitor with a capacitor current, and displace the ferromagneticplunger in the first direction to displace the engagement rod and engagethe first rocker with the toothed wheel. The method also includesreducing the first directional current to hold the ferromagnetic plungerand keep the first rocker engaged with the toothed wheel, and removingthe first directional current. In some example embodiments, the methodalso includes increasing the first directional current prior to removingthe first directional current. In an example embodiment, the step ofincreasing the first directional current increases an inductance in thewire coil.

In some example embodiments, after the step of removing the firstdirectional current, a current path is created between the capacitor andthe wire coil. In some example embodiments, the capacitor currentenergizes the current path so that a coil current in the wire coilalternates between the first directional current and the seconddirectional current as the capacitor is charged and discharged. In anexample embodiment, the alternating coil current demagnetizes the wirecoil after a time period. In some example embodiments, a magnetism inthe wire coil alternates between a positive value and a negative valueas the coil current alternates between the first directional current andthe second directional current. In an example embodiment, a peakmagnetism approaches zero with each cycle of the alternating coilcurrent.

Other example embodiments broadly comprise a transmission actuator for avehicle including a solenoid and a solenoid control circuit. Thesolenoid has an iron core, a wire coil wrapped around the iron core, thewire coil having a resistance and an inductance, a capacitor connectedto opposite ends of the wire coil, and a ferromagnetic plunger disposedradially inside the wire coil. The ferromagnetic plunger is arranged tolinearly displace in a first direction when a first directional currentis applied to the wire coil and arranged to linearly displace in asecond direction, opposite the first direction, when a seconddirectional current, opposite the first directional current, is appliedto the wire coil. The solenoid control circuit is arranged to supply thefirst directional current when the solenoid control circuit is energizedby a power source, and supply a decaying alternating current thatincludes the first directional current and the second directionalcurrent when the solenoid control circuit is de-energized from the powersource.

Other example embodiments broadly comprise a method of controlling thetransmission actuator including applying the first directional currentwith the solenoid control circuit to magnetize the wire coil, charge thecapacitor with a capacitor current, and displace the ferromagneticplunger in the first direction. The method also includes reducing thefirst directional current to hold the ferromagnetic plunger and removingthe first directional current. In an example embodiment, the methodincludes increasing the first directional current to increase aninductance in the wire coil prior to removing the first directionalcurrent.

In some example embodiments, after the step of removing the firstdirectional current, the capacitor current energizes a current pathbetween the capacitor and the wire coil so that a coil current in thewire coil alternates between the first directional current and thesecond directional current as the capacitor is charged and discharged,demagnetizing the wire coil after a time period. In an exampleembodiment, a magnetism in the wire coil alternates between a positivevalue and a negative value as the coil current alternates between thefirst directional current and the second directional current, and a peakmagnetism in the wire coil approaches zero with each cycle of thealternating coil current.

BRIEF DESCRIPTION OF THE DRAWINGS

Various embodiments are disclosed, by way of example only, withreference to the accompanying schematic drawings in which correspondingreference symbols indicate corresponding parts, in which:

FIG. 1 is a schematic block diagram of a wedge clutch with residualmagnetism attenuation;

FIG. 2 is a schematic wiring diagram of an attenuating circuit in FIG. 1;

FIG. 3 is a graph of magnetic flux density and magnetic field strength;

FIG. 4 is a graph of electrical current through a coil and time, showingan oscillating waveform;

FIG. 5 is an exploded view of an example wedge clutch with residualmagnetism attenuation shown in FIG. 1 ;

FIG. 6 is a front view of the wedge clutch with residual magnetismattenuation shown in FIG. 5 ;

FIG. 7 is a cross-sectional view of an electromagnetic actuator of thewedge clutch with residual magnetism attenuation shown in FIG. 5 ;

FIG. 8 is a front view of a wedge plate of the wedge clutch withresidual magnetism attenuation shown in FIG. 5 ;

FIG. 9 is a front view of a wedge plate of the wedge clutch withresidual magnetism attenuation shown in FIG. 5 ;

FIG. 10 is a front view of inner races of the wedge clutch with residualmagnetism attenuation shown in FIG. 5 ;

FIG. 11 is a back view of a wedge plate of the wedge clutch withresidual magnetism attenuation shown in FIG. 5 ;

FIG. 12 is a back view of a wedge plate of the wedge clutch withresidual magnetism attenuation shown in FIG. 5 ;

FIG. 13 is a cross-sectional view generally along line 13-13 in FIG. 6 ;

FIG. 14 is an exploded view of an example wedge clutch with residualmagnetism attenuation;

FIG. 15 is a front view of the wedge clutch with residual magnetismattenuation shown in FIG. 14 ;

FIG. 16 is a front view of a wedge plate of the wedge clutch withresidual magnetism attenuation shown in FIG. 14 ;

FIG. 17 is a front view of a wedge plate of the wedge clutch withresidual magnetism attenuation shown in FIG. 14 ;

FIG. 18 is a front view of an inner race of the wedge clutch withresidual magnetism attenuation shown in FIG. 14 ;

FIG. 19 is a cross-sectional view generally along line 19-19 in FIG. 15;

FIG. 20 is front view of an example wedge clutch with residual magnetismattenuation;

FIG. 21 is an enlarged view of region 21 in FIG. 20 ;

FIG. 22 is a schematic cross-sectional view of a pump, with residualmagnetism attenuation;

FIG. 23 is an exploded view of the pump shown in FIG. 22 ; and

FIG. 24 is a front view of a stator, a rotor and a swash plate of thepump shown in FIG. 22 .

FIG. 25 illustrates a perspective view of a transmission actuator and atoothed wheel according to an example embodiment.

FIG. 26 illustrates a cross-sectional view of the transmission actuatorand toothed wheel of FIG. 25 .

FIG. 27 illustrates a schematic view of a first electrical circuit forthe transmission actuator of FIG. 25 .

FIG. 28 illustrates a schematic view of a second electrical circuit forthe transmission actuator of FIG. 25 .

FIG. 29 illustrates a first pair of graphs showing current and magnetismduring a first example engagement and disengagement of the transmissionactuator of FIG. 25 .

FIG. 30 illustrates a second pair of graphs showing current andmagnetism during a second example engagement and disengagement of thetransmission actuator of FIG. 25 .

DETAILED DESCRIPTION

At the outset, it should be appreciated that like drawing numbers ondifferent drawing views identify identical, or functionally similar,structural elements of the disclosure. It is to be understood that thedisclosure as claimed is not limited to the disclosed aspects.

Furthermore, it is understood that this disclosure is not limited to theparticular methodology, materials and modifications described and assuch may, of course, vary. It is also understood that the terminologyused herein is for the purpose of describing particular aspects only,and is not intended to limit the scope of the present disclosure.

Unless defined otherwise, all technical and scientific terms used hereinhave the same meaning as commonly understood to one of ordinary skill inthe art to which this disclosure belongs. It should be understood thatany methods, devices or materials similar or equivalent to thosedescribed herein can be used in the practice or testing of thedisclosure.

FIG. 1 is a schematic block diagram of wedge clutch 100 with residualmagnetism attenuation.

FIG. 2 is a schematic wiring diagram of an attenuating circuit shown inFIG. 1 . The following should be viewed in light of FIGS. 1 and 2 .Wedge clutch 100 includes: axis of rotation AR; outer race 102; innerrace 104; at least one wedge plate 106 radially disposed between innerrace 104 and outer race 102; and at least one electromagnetic actuator107 including attenuating circuit 108. Each electromagnetic actuator 107includes ferromagnetic material FM and coil 109 arranged to be energizedby source voltage Vs from electrical power source EPS to generatemagnetic field MF (only partially displayed in FIG. 2 ). In the exampleof FIGS. 1 and 2 , each electromagnetic actuator 107 includes at leastone coil core piece 110 with: at least one end 105 fixedly connected toat least one wedge plate wedge plate 106; and at least one end 111enclosed by coil 109. The dashed lines in FIG. 2 enclose and designateelements that are connected to circuit 108, but not necessarily includedwith circuit 108. In an example embodiment (not shown), elementsenclosed and designated by the dashed lines in FIG. 2 are included incircuit 108. Note that coil 109 functions as an inductor.

Magnetic field MF displaces at least one wedge plate 106, with respectto outer race 102 or inner race 104, to switch wedge clutch 100 between:a first locked mode of wedge clutch 100; and a first free-wheel mode ofwedge clutch 100. In the first locked mode, inner race 104, wedge plate106, and outer race 102 are non-rotatably connected for rotation ofinner race 104 in one of circumferential direction CD1 or oppositecircumferential direction CD2. In the first free-wheel mode of wedgeclutch 100, inner race 104 is rotatable, with respect to outer race 102,in the one of circumferential direction CD1 or CD2.

Each attenuating circuit 108 includes: capacitor 112 wired in parallelwith coil 109 and switch 113 wired to capacitor 112. During the firstfree-wheel mode of wedge clutch 100: switch 113 is arranged to connectcapacitor 112 and coil 109 to electrical ground EG; and electrical powersource EPS is arranged to energize coil 109 and charge capacitor 112with capacitor voltage Vc. Following, or concurrent with, an initiationof the first locked mode: switch 113 is arranged to electrically isolatecapacitor 112 and coil 109 from electrical ground EG; and capacitor 112is arranged to discharge voltage Vc through coil 109.

Following the initiation of the first locked mode, voltage Vc incapacitor 112 and a voltage drop across coil 109 are arranged toalternately drive: electrical current EC1 through coil 109 in directionD1; and electrical current EC2 through coil 109 in direction D2,opposite direction D1. Following the initiation of the first lockedmode, current EC1 and current EC2: randomize residual magnetic fields inelectromagnetic actuator 107 or wedge plate 106; and attenuate residualmagnetic saturation in electromagnetic actuator 107 or wedge plate 106.As further described below, when coil 109 and charged capacitor 112(voltage Vc is present) are isolated from ground EG by switch 113,coil/inductor 109 and capacitor 112 operate as oscillating circuit OC,in which voltage Vc is discharged through currents EC1 and EC2.

In an example embodiment, attenuating circuit 108 includes switch 114.Switch 114: is electrically connected to capacitor 112 and coil 109; andarranged to electrically connect to electrical power source EPS.Following the initiation of the first locked mode, switch 114 isarranged to electrically isolate capacitor 112 and coil 109 fromelectrical power source EPS.

FIG. 3 is a graph of magnetic flux density B and magnetic field strengthH. The following should be viewed in light of FIGS. 1 through 3 . Asenergy is applied to coil 109, magnetic flux is introduced into materialFM, causing magnetic field MF to form. When sufficient power issupplied, magnetic field MF reaches saturation point, B_sat shown inFIG. 3 . When the power is removed from coil 109, magnetic field MF inmaterial FM decreases but does not disappear completely. The remainingmagnetic field MF is governed by the retentivity, or residual magnetism,of material FM, shown as B_r in FIG. 3 . This residual field MF can bedetrimental to the operation of some devices. For example as furtherdescribed below, residual field MF can prevent proper operation ofactuator 107.

Attenuating (continuously decreasing) alternating current currents EC1and EC2 through coil 109 create a constantly reversing flux field inferromagnetic material FM. In FIG. 2, the direction (direction D1) ofmagnetic field MF corresponds to current EC1. The attenuating andreversing flux fields randomize the magnetic orientation of material FM,removing residual magnetization in material FM. As noted above, whenpower is removed from coil 109, oscillating circuit OC oscillates andrandomizes the magnetic domains in material FM as energy in the form ofheat generated by the electrical resistance of coil 109 and currents EC1and EC2 passing through coil 109. Capacitor 112 can be selected togenerate a desired frequency of oscillations for a particular size ofcoil 109, to completely remove the residual magnetism noted above.

FIG. 4 is a graph of electrical current through coil 109 (current EC1and EC2 on the Y axis) and time (X axis) showing oscillating waveformOW. The following should be viewed in light of FIGS. 1 through 4 . Whenoscillating circuit OC begins oscillating: coil 109 attempts to maintaina constant current through coil 109, while capacitor 112 attempts tomaintain a constant voltage Vc. For example, coil 109 pushes current EC1in direction D1, thus inducing a voltage drop across coil 109. Capacitor112 opposes the voltage drop by driving current EC2 in oppositedirection D2. The oscillating push and pull of currents EC1 and EC2between coil 109 and capacitor 112 continues until power in coil 109 andcapacitor 112 is dissipated as heat through the electrical resistance ofcoil 109.

No control or intervention is required to generate the waveform in FIG.4 once switches 113 and 114 are opened. That is, the oscillating pushand pull of currents EC1 and EC2 between coil 109 and capacitor 112begins when switch 113 is opened and continues without further activecontrol. The electrical resistance of coil 109 determines the decay timeof the oscillations in FIG. 4 . Increasing the resistance increases thespeed at which waveform OW decreases to zero. In cases in which theresistance and inductance of coil 109 are fixed to accommodate otherdesign considerations of actuator 107, capacitance values for capacitor112 are selectable to achieve a desired oscillation frequency and decaytime. Thus, circuit 108 has the modularity for removing residualmagnetism in many sizes of motor or solenoid systems.

In an example embodiment, switch 113 is an n-type transistor (either annpn or n-MOSFET). In the discussion that follows, ‘transistor 113’ isused in place of ‘switch 113.’ Applying control voltage CV1 from controlunit CU (part of the vehicle or system including actuator 107 andcircuit 108) to gate G1 of transistor 113 switches transistor 113 on,creating a current path from coil 109 to ground EG. The current pathenables current to flow through coil 109, creating magnetic field MF.Removing control voltage CV1 from gate G1 switches off transistor 113,disrupting the current path through coil 109 to ground EG.

Thus, when switched off, transistor 113 isolates coil 109/capacitor 112and oscillating circuit OC from ground EG. Once isolated from ground EG,oscillating circuit OC begins oscillating as described above to createcurrents EC1 and EC2. Thus, there is no loss of the power in oscillatingcircuit OC through bleeding into ground EG. That is, a maximum amount ofthe power in oscillating circuit OC is available for creating theattenuating and reversing flux fields noted above.

In an example embodiment, switch 114 is a p-type transistor (pnp orPMOS). In the discussion that follows, ‘transistor 114’ is used in placeof ‘switch 114.’ By switching transistor 114 on, current flow throughcoil 109 is enabled as transistor 114 is switched on. By switching offtransistor 114, power source EPS is isolated from coil 109, providingadditional circuit protection and isolation when transistor 113 isswitched off. In an example embodiment, n-type transistor 115 is wiredto gate G2 of transistor 114 to enable easier switching of transistor114. In general, control voltages, such as CV1, are less than voltageVs. Transistor 115 is switched on by control voltage CV2, at gate G3 oftransistor 115, less than voltage Vs from source EPS. When voltage atgate G2 equals voltage Vs, transistor 114 is switched off.

As noted above, to switch coil 109 on, transistor 114 is switched on. Toswitch transistor 114 on, control voltage CV2 is applied to gate G3,switching transistor 115 on, creating a ground path from gate G2, suchthat voltage at gate G2 is less than voltage Vs. Removing controlvoltage CV2 from gate G3 switches transistor 115 off, isolating gate G2from ground and applying voltage Vs to gate G2 to switch transistor 114off. In an example embodiment, resistor R1 with value R is added tocircuit 108 to provide a voltage drop path.

FIG. 5 is an exploded view of example wedge clutch 100 with residualmagnetism attenuation shown in FIG. 1 .

FIG. 6 is a front view of wedge clutch 100 with residual magnetismattenuation shown in FIG. 5 .

FIG. 7 is a cross-sectional view of electromagnetic actuator 107A shownin FIG. 5 . The following should be viewed in light of FIGS. 1 through 7. Wedge clutch 100 includes: axis of rotation AR; outer race 102; innerrace 104; wedge plates 106A and 106B; and electromagnetic actuator 107A.Wedge plates 106A and 106B are radially disposed between inner race 104and outer race 102. In an example embodiment, wedge plates 106A and 106Bincludes slots SL1 extending radially inwardly from radially outercircumference ROC and slots SL2 extending radially outwardly fromradially inner circumference RIC. Attenuating circuit 108 for actuator107A is schematically presented in FIG. 5 . An actual configuration andposition of circuit 108 is dependent at least in part upon theconfiguration of the electrical system powering actuator 107A. Ingeneral, a reference character “In the example of FIG. 5 ,electromagnetic actuator 107A includes coil 109; bobbin 115; coil corepiece 110A; and coil core piece 110B. Coil core piece 110A includes: end111A disposed within coil 109; and end 105A connected to wedge plates106A and 106B. Coil core piece 110B includes: end 111B disposed withincoil 109; and end 105B connected to wedge plates 106A and 106B. Toaccommodate the radially inward displacement and radial contraction ofwedge plates 106A and 106B described below, ends 111A and 111B areseparated by air gap 118.

In the example of FIG. 5 , inner race 104 is arranged to receiverotational torque. In a first locked mode of wedge clutch 100, innerrace 104, wedge plates 106A and 106B, and outer race 102 arenon-rotatably connected for rotation of inner race 104 incircumferential direction CD1. In a first free-wheel mode of wedgeclutch 100, inner race 104 is rotatable, with respect to the outer race102, in circumferential direction CD1. By “non-rotatably connected”components, we mean that: the components are connected so that wheneverone of the components rotates, all the components rotate; and relativerotation between the components is not possible. Radial and/or axialmovement of non-rotatably connected components with respect to eachother is possible, but not required.

To transition from the first locked mode to the first free-wheel mode,electromagnetic actuator 107A is arranged to be energized to: draw ends111A and 111B toward each other; displace wedge plates 106A and 106Bradially inwardly; and radially contract wedge plates 106A and 106B. Totransition from the first free-wheel mode to the first locked mode:electromagnetic actuator 107A is arranged to be de-energized; and wedgeplates 106A and 106B are arranged to expand radially outwardly toinitiate or increase frictional contact between wedge plates 106A and106B and outer race 102. For example, wedge plates 106A and 106B arepreloaded with a radially outwardly expanding force that is overcome byelectromagnetic actuator 107A to transition to the first free-wheelmode, and which results in the radial expansion characterizing thetransition to the first locked mode.

FIG. 8 is a front view of wedge plate 106A of wedge clutch 100 withresidual magnetism attenuation shown in FIG. 5 . The following should beviewed in light of FIGS. 1 through 8 . Wedge plate 106A includes:circumferential end 120; and circumferential end 122. Wedge plate 106Ais discontinuous between end 120 and end 122. For example, ends 120 and122 are separated by gap 124 in circumferential direction CD1. End 105Aof coil core piece 110A of electromagnetic actuator 107A is fixedlyconnected to circumferential end 120. End 105B of coil core piece 110Bof electromagnetic actuator 107A is fixedly connected to circumferentialend 128.

FIG. 9 is a front view of wedge plate 106B of wedge clutch 100 withresidual magnetism attenuation shown in FIG. 5 . The following should beviewed in light of FIGS. 1 through 9 . Wedge plate 106B includes:circumferential end 126; and circumferential end 128. Wedge plate 106Bis discontinuous between end 126 and end 128. For example, ends 126 and128 are separated by gap 130 in circumferential direction CD1. End 105Aof coil core piece 110A of electromagnetic actuator 107A is fixedlyconnected to circumferential end 126. End 105B of coil core piece 110Bof electromagnetic actuator 107A is fixedly connected to circumferentialend 128. In an example embodiment, end 105A of coil core piece 110A isfixedly connected to circumferential ends 120 and 126 with a bolt 132and end 105B of coil core piece 110B is fixedly connected tocircumferential ends 122 and 128 with a bolt 132. However, it should beunderstood that any means known in the art can be used to fixedlyconnect coil core pieces 110A and 110B to wedge plates 106A and 106B.

To transition from the first locked mode to the first free-wheel mode,electromagnetic actuator 107A is arranged to be energized to: bringcircumferential end 120 and circumferential end 122 toward each incircumferential direction CD1 or circumferential direction CD2, oppositecircumferential direction CD1; and bring circumferential end 126 andcircumferential end 128 toward each in circumferential direction CD1 orcircumferential direction CD2. Stated otherwise, electromagneticactuator 107A is arranged to be energized to decrease gaps 124 and 130.

FIG. 10 is a front view of inner races of wedge clutch 100 with residualmagnetism attenuation shown FIG. 5 . The following should be viewed inlight of FIGS. 1 through 10 . Wedge plate 106A includes ramps 134. Wedgeplate 106B includes ramps 136. Inner race 104 includes ramps 138. Eachramp 134 is in contact with a respective ramp 138. Each ramp 136 is incontact with a respective ramp 138. Each ramp 134, each ramp 136, andeach ramp 138 slope radially inwardly in circumferential direction CD1.To transition from the first locked mode to the first free-wheel mode,electromagnetic actuator 107A is arranged to: slide at least one ramp134 radially inwardly along at least one ramp 138; and slide at leastone ramp 136 radially inwardly along at least one ramp 138.

FIG. 11 is a back view of wedge plate 106C of wedge clutch 100 withresidual magnetism attenuation shown in FIG. 5 .

FIG. 12 is a back view of wedge plate 106D of wedge clutch 100 withresidual magnetism attenuation shown FIG. 5 . The following should beviewed in light of FIGS. 1 through 12 . In an example embodiment, wedgeclutch 100 includes: inner race 140 non-rotatably connected to innerrace 104 with bolts 142; wedge plates 106C and 106D; and electromagneticactuator 107B. Any means known in the art can be used to non-rotatablyconnect inner races 104 and 140. In an example embodiment (not shown),inner races 104 and 140 are a single monolithic structure. Wedge plates106C and 106D are radially disposed between inner race 140 and outerrace 102. The discussion for actuator 107A is applicable to actuator107B unless noted otherwise.

In an example embodiment, wedge plates 106C and 106D includes slots SL1extending radially inwardly from radially outer circumference ROC andslots SL2 extending radially outwardly from radially inner circumferenceRIC. Ends 105A and 105B of actuator 107B are connected to wedge plates106C and 106D.

In a second locked mode of wedge clutch 100, inner race 140, wedgeplates 106C and 106D, and outer race 102 are non-rotatably connected forrotation of inner race 140 in circumferential direction CD2. In a secondfree-wheel mode of wedge clutch 100, inner race 140 is rotatable, withrespect to outer race 102, in circumferential direction CD2.

To transition from the second locked mode to the second free-wheel mode,electromagnetic actuator 107B is arranged to be energized to: draw ends111A and 111B of actuator 107B toward each other; displace wedge plates106C and 106D radially inwardly; and radially contract wedge plates 106Cand 106D. To transition from the second free-wheel mode to the secondlocked mode: electromagnetic actuator 107B is arranged to bede-energized; and wedge plates 106C and 106D are arranged to expandradially outwardly to initiate or increase frictional contact betweenwedge plates 106C and 106D and outer race 102. For example, wedge plates106C and 106D are preloaded with a radially outwardly expanding forcethat is overcome by electromagnetic actuator 107B to transition to thesecond free-wheel mode, and which results in the radial expansioncharacterizing the transition to the second locked mode.

Wedge plate 106C includes: circumferential end 144; and circumferentialend 146. Wedge plate 106C is discontinuous between end 144 and end 146.For example, ends 144 and 146 are separated by gap 148 incircumferential direction CD1. End 105A of coil core piece 110A ofelectromagnetic actuator 107B is fixedly connected to circumferentialend 144. End 105B of coil core piece 110B of electromagnetic actuator107B is fixedly connected to circumferential end 146. In an exampleembodiment, end 105A is fixedly connected to circumferential end 144with bolt 132 and end 105B is fixedly connected to circumferential end146 with bolt 132. However, it should be understood that any means knownin the art can be used to fixedly connect end 105A of coil core piece110A to circumferential end 144 and to fixedly connect end 105B of coilcore piece 110B to circumferential end 146.

Wedge plate 106D includes: circumferential end 150; and circumferentialend 152. Wedge plate 106D is discontinuous between end 150 and end 152.For example, ends 150 and 152 are separated by gap 154 incircumferential direction CD1. End 105A of coil core piece 110A ofelectromagnetic actuator 107B is fixedly connected to circumferentialend 150. End 105B of coil core piece 110B of electromagnetic actuator107B is fixedly connected to circumferential end 152. In an exampleembodiment, end 105A of coil core piece 110A is fixedly connected tocircumferential end 150 with bolt 132 and end 105B of coil core piece110B is fixedly connected to circumferential end 152 with bolt 132.However, it should be understood that any means known in the art can beused to fixedly connect end 105A to circumferential end 150 and tofixedly connect end 105B to circumferential end 152.

To transition from the second locked mode to the second free-wheel mode,electromagnetic actuator 107B is arranged to be energized to: bringcircumferential end 144 and circumferential end 146 toward each incircumferential direction CD1 or circumferential direction CD2; andbring circumferential end 150 and circumferential end 152 toward each incircumferential direction CD1 or circumferential direction CD2. Statedotherwise, electromagnetic actuator 107B is arranged to be energized todecrease gaps 148 and 154.

Wedge plate 106C includes ramps 156, wedge plate 106D includes ramps158, and inner race 140 includes ramps 160. Each ramp 156 is in contactwith a respective ramp 160. Each ramp 158 is in contact with arespective ramp 160. Each ramp 156, each ramp 158, and each ramp 160,slope radially inwardly in circumferential direction CD2. To transitionfrom the second locked mode to the second free-wheel mode,electromagnetic actuator 107B is arranged to: slide at least one ramp156 radially inwardly along at least one ramp 160; and slide at leastone ramp 158 radially inwardly along at least one ramp 160.

FIG. 13 is a cross-sectional view generally along line 13-13 in FIG. 6 .The following should be viewed in light of FIGS. 1 through 13 . In anexample embodiment: wedge plate 106A includes chamfer 162; wedge plate106B includes chamfer 164; and inner race 104 includes groove 166.Chamfers 162 and 164 are disposed at least partly in groove 166. In anexample embodiment: wedge plate 106C includes chamfer 168; wedge plate106D includes chamfer 170; and inner race 140 includes groove 172.Chamfers 168 and 170 are disposed at least partly in groove 172. In anexample embodiment: inner race 104 includes slot 174, in which actuator107A is located; and inner race 140 includes slot 176, in which actuator107B is located. Electrical power is supplied to electromagneticactuators 107A and 107B by any means known in the art. In an exampleembodiment, clutch 100 includes slip ring retainer 178 and slip ring 180for supplying electrical power to electromagnetic actuators 107A and107B.

FIG. 14 is an exploded view of example wedge clutch 220 with residualmagnetism attenuation. Wedge clutch 220 includes: axis of rotation AR;outer race 222; inner race 224; wedge plates 106E and 106F; andelectromagnetic actuator 107C including attenuating circuit 108. Wedgeplates 106E and 106F are radially disposed between inner race 224 andouter race 222. In the example of FIG. 14 , inner race 224 is arrangedto receive rotational torque. The discussion for electromagneticactuator 107A is applicable to electromagnetic actuator 107C in FIG. 14. Attenuating circuit 108 for actuator 107C is schematically presentedin FIG. 14 . An actual configuration and position of circuit 108 isdependent at least in part upon the configuration of the electricalsystem powering actuator 107C.

FIG. 15 is a front view of wedge clutch 220 with residual magnetismattenuation shown in FIG. 14 ;

FIG. 16 is a front view of wedge plate 106E of wedge clutch 220 withresidual magnetism attenuation shown FIG. 14 . The following should beviewed in light of FIGS. 14 through 16 . In an example embodiment, wedgeplates 106E and 106F includes slots SL1 extending radially inwardly fromradially outer circumference ROC and slots SL2 extending radiallyoutwardly from radially inner circumference MC. End 105A of actuator107C is connected to wedge plates 106E and 106F. End 105B of actuator107C is connected to wedge plates 106E and 106F.

In a locked mode of wedge clutch 220, inner race 224, wedge plates 106Eand 106F, and outer race 222 are non-rotatably connected for rotation ofinner race 224 in circumferential direction CD1 or in circumferentialdirection CD2. In a free-wheel mode of wedge clutch 220, inner race 224is rotatable, with respect to outer race 222 in circumferentialdirection CD1 or in circumferential direction CD2.

To transition from the locked mode to the free-wheel mode,electromagnetic actuator 107C is arranged to be energized to: draw ends111A and 111B of actuator 107C toward each other; displace wedge plates106E and 106F radially inwardly; and radially contract wedge plates 106Eand 106F. To transition from the free-wheel mode to the locked mode:electromagnetic actuator 107C is arranged to be de-energized; and wedgeplates 106E and 106F are arranged to expand radially outwardly toinitiate or increase frictional contact between wedge plates 106E and106F and outer race 222. For example, wedge plates 106E and 106F arepreloaded with a radially outwardly expanding force that is overcome byelectromagnetic actuator 107C to transition to the free-wheel mode, andwhich results in the radial expansion characterizing the transition tothe locked mode.

Wedge plate 106E includes: circumferential end 226; and circumferentialend 228. Wedge plate 106E is discontinuous between end 226 and end 228.For example, ends 226 and 228 are separated by gap 230 incircumferential direction CD1. End 105A of coil core piece 110A isfixedly connected to circumferential end 226. End 105B of coil corepiece 110B is fixedly connected to circumferential end 228.

FIG. 17 is a front view of wedge plate 106F of electromagneticselectable wedge clutch 220 shown in FIG. 14 . The following should beviewed in light of FIGS. 14 through 17 . Wedge plate 106F includes:circumferential end 232; and circumferential end 234. Wedge plate 106Fis discontinuous between end 232 and end 234. For example, ends 232 and234 are separated by gap 236 in circumferential direction CD1. End 105Aof coil core piece 110A is fixedly connected to circumferential end 232.End 105B of coil core piece 110B is fixedly connected to circumferentialend 234. In an example embodiment, end 105A of coil core piece 110A isfixedly connected to circumferential ends 226 and 232 with a bolt 237and end 105B of coil core piece 110B is fixedly connected tocircumferential ends 228 and 234 with a bolt 237. However, it should beunderstood that any means known in the art can be used to fixedlyconnect coil core pieces 110A and 110B to wedge plates 106E and 106F.

To transition from the locked mode to the free-wheel mode,electromagnetic actuator 107C is arranged to be energized to: bringcircumferential end 226 and circumferential end 228 toward each incircumferential direction CD1 or circumferential direction CD2; andbring circumferential end 232 and circumferential end 234 toward each incircumferential direction CD1 or circumferential direction CD2. Statedotherwise, electromagnetic actuator 107C is arranged to be energized todecrease gaps 230 and 236.

FIG. 18 is a front view of inner race 224 of wedge clutch 220 withresidual magnetism attenuation shown in FIG. 14 . The following shouldbe viewed in light of FIGS. 14 through 18 . Wedge plate 106E includesramps 238 and 239. Wedge plate 106F includes ramps 240 and 241. Innerrace 224 includes ramps 242 and 243. Each ramp 238 is in contact with arespective ramp 242. Each ramp 239 is in contact with a respective ramp243. Each ramp 240 is in contact with respective ramp 242. Each ramp 241is in contact with a respective ramp 243. Ramps 238, 240, and 242 sloperadially inwardly in circumferential direction CD2. Ramps 239, 241, and243 slope radially inwardly in circumferential direction CD1.

FIG. 19 is a cross-sectional view generally along line 19-19 in FIG. 15. The following should be viewed in light of FIGS. 14 through 19 . In anexample embodiment: wedge plate 106E includes chamfer 244; wedge plate106F includes chamfer 246; and inner race 224 includes groove 248.Chamfers 244 and 246 are disposed at least partly in groove 248. In anexample embodiment: inner race 224 includes slot 250, in which actuator107C is located. Electrical power is supplied to actuator 107C by anymeans known in the art. In an example embodiment, clutch 220 includesslip ring retainer 252 and slip ring 254 for supplying electrical powerto actuator 107C.

It should be understood that clutches 100 and 220 are not limited to theexample embodiments shown and described. For example, thecircumferential directions in which respective ramps slope can bereversed. For example, different numbers of ramps for wedge plates andinner races are possible.

FIG. 20 is a front view of example wedge clutch 300 with residualmagnetism attenuation.

FIG. 21 is an enlarged view of region 21 in FIG. 20 . The followingshould be viewed in light of FIGS. 20 and 21 . Wedge clutch 300includes: outer race 302; inner race 304; wedge plate 306 radiallydisposed between inner race 304 and outer race 302; and electromagneticactuator 308 including attenuating circuit 108. Electromagnetic actuator308 is embedded in wedge plate 306 and includes coil 310 and coil corepiece 312 with: end 314 fixedly connected to wedge plate 306; and end316 enclosed by coil 310. Coil 310 is wrapped about fingers 318 formedby wedge plate 306. That is, wedge plate 306 forms a portion of actuator308. Attenuating circuit 108 for actuator 308 is schematically presentedin FIG. 21 . An actual configuration and position of circuit 108 isdependent at least in part upon the configuration of the electricalsystem powering actuator 308. Wedge plate 306 is analogous toferromagnetic material FM discussed in FIGS. 1 through 4 . Actuator 308has only one single coil core piece 310.

In the configuration of FIG. 20 , inner race 304 is arranged to receiverotational torque. Wedge plate 306 includes ramps 320 and 322. Innerrace 304 includes: ramps 324, engaged with ramps 320; and ramps 326engaged with ramps 322. The discussion for FIGS. 14 through 19 regardingwedge plate 106E, ramps 238, 239, 242, and 243 is applicable to wedgeplate 306, and ramps 320, 322, 324, and 326, respectively.

The discussion for FIGS. 14 through 19 regarding operation of clutch 220is generally applicable to clutch 300. Like clutch 220, clutch 300 has afree-wheel operating mode and a locked operating mode. To transitionfrom the locked mode to the free-wheel mode, actuator 308 is energizedto displace coil core piece 310 in circumferential direction CD1 todisplace wedge plate 306 radially inwardly and radially contract wedgeplate 306 so that inner race 304 and wedge plate 306 are rotatable withrespect to outer race 302. To transition from the free-wheel mode to thelocked mode, actuator 308 is de-energized and wedge plate 306 displacesradially outwardly to initiate or increase frictional contact betweenwedge plate 306 and outer race 302 to non-rotatably connect inner race304, wedge plate 306, and outer race 302.

As noted above, when electrical power is removed from coil 109, magneticfield MF in material FM decreases but does not disappear completely. Theresidual field MF can be detrimental to the operation of clutches 100and 200. For example, for clutch 100 and actuator 107A, a residual fieldMF can continue to urge ends 111A and 111B toward each other during thetransition from the first free-wheel mode to the first locked mode. As aresult, wedge plates 106A and 106B may not expand and displace radiallyoutwardly to engage outer race 102 with sufficient frictional force tocause wedge plates 106A and 106B to rotate with outer race 102 and withrespect to inner race 104. Without the preceding rotations, thetransition to the locked mode does not occur. The residual field MFcould prevent the transition from the first free-wheel mode to the firstlocked mode, or could delay the transition from the first free-wheelmode to the first locked mode, either of which would be detrimental tooperation of clutch 100 and any device, such as a power train, includingclutch 100.

Attenuating circuit 108 for actuator 107A eliminates a residual field MFin actuator 107A as described above in the discussion for FIGS. 1through 4 . Thus, circuit 108 in actuator 107A eliminates potentialproblems noted above regarding operation of clutch 100. The precedingdiscussion regarding a residual field MF in actuator 107A is applicableto actuator 107B and 107C.

When electrical power is removed from coil 310, a magnetic field inwedge plate 306 decreases but does not disappear completely. A residualmagnetic field can be detrimental to the operation of clutch 300. Forexample, a residual magnetic field can continue to urge end 316 indirection CD1 during the transition from the free-wheel mode to thelocked mode. As a result, wedge plate 306 may not expand and displaceradially outwardly to engage outer race 302 with sufficient frictionalforce to cause wedge plate 306 to rotate with outer race 302 and withrespect to inner race 304. Without the preceding rotations, thetransition to the locked mode does not occur. The residual magneticfield could prevent the transition from the free-wheel mode to thelocked mode, or could delay the transition from the free-wheel mode tothe locked mode, either of which would be detrimental to operation ofclutch 300 and any device, such as a power train, including clutch 300.

Attenuating circuit 108 for actuator 308 eliminates a residual magneticfield in wedge plate 308 as described above for actuator 107A. Thus,circuit 108 in actuator 308 eliminates potential problems noted aboveregarding operation of clutch 300.

FIG. 22 is a schematic cross-sectional view of pump 10, with residualmagnetism attenuation.

FIG. 23 is an exploded view of pump 10 shown in FIG. 22 .

FIG. 24 is a front view of a stator, a rotor and a swash plate of thepump shown in FIG. 22 . The following should be viewed in light of FIGS.22 through 24 . Pump 10 includes: fluid inlet section 12 of a housing;fluid outlet section 14 of the housing; stator 16 axially between fluidinlet section 12 and fluid outlet section 14; and rotor 18 axiallybetween fluid inlet section 12 and fluid outlet section 14. Rotor 18 andstator 16 define fluid flow space 20 radially therebetween. Pump 10 alsoincludes: movable inlet guide, or swash plate, 22 configured for guidingfluid flow from fluid inlet section 12 into fluid flow space 20; andmovable outlet guide, for swash plate, 24 configured for guiding fluidflow from fluid flow space 20 into fluid outlet section 14.

Stator 16 is provided with electrical windings 26 for generatingelectromagnetic forces in stator 16 to urge rotor 18 toward stator 16such that rotor 18 rotates inside of stator 16. In an exampleembodiment, stator 16 is provided with six electrical windings 26, butin other embodiments, stator 16 may be provided with any other amountsof windings 26 greater than three. Windings 26 are each wrapped aroundone of legs 28 of stator 16. Stator 16 includes cylindrical ring 30defining an outer circumference of stator 16, with each leg 28protruding radially inward from cylindrical ring 30. Each legs 28includes base 32 extending radially inward from an inner circumferenceof cylindrical ring 30, two branches 34 extending circumferentially froma radially inner end of base 32 in opposite circumferential directions,and rounded radially innermost tip 36 protruding radially inward frombranches 34. Windings 26 are wrapped around base 32 and held radially inplace by the inner circumferential surface of cylindrical ring 30 andthe outer circumferential surfaces of branches 34. In an exampleembodiment (not shown) insulation layers are provided over windings 26to insulate windings from fluid flow space 20.

Rotor 18 is substantially star shaped and includes radially outwardlyextending protrusions 38. In an example embodiment, rotor 18 includesfive protrusions 38. However, rotor 18 may include other amounts ofprotrusions 38, with the amount of protrusions 38 being one less thanthe number of windings 26. Protrusions 38 each include radiallyoutermost rounded tip 40. Rotor 18 is configured such that duringrotation, protrusions 38 sequentially enter into slots 42 betweenprotrusions 38 to continuously vary the configuration of fluid flowspace 20.

When an electric current is sent through any one of windings 26 amagnetic field is created which pulls rotor 18 toward that winding 26 inorder to complete a magnetic circuit formed by legs 28 of the stator. Asrotor 18 moves toward the winding 26, rotor 18 displaces fluid, withwhich fluid flow space 20 between rotor 18 and stator 16 is filled,creating pressure. The movement of rotor 18 within stator 16 separatesfluid flow space 20 into portion 20 a pressurized to force fluid out ofoutlet section 14 and a portion 20 b that forms a vacuum to draw fluidinto fluid flow space 20 from inlet section 12. As rotor 18 rotateswithin stator 16, the locations of portion 20 a and portion 20 b rotateabout a center axis 44, with portion 20 a being oriented on the oppositeradial side of rotor 18 as portion 20 b during the rotation.

In order to properly align inlet section 12 with portion 20 b whileisolating inlet section 12 from portion 20 a, pump 10 includes a movableinlet guide in the form of inlet swash plate 22 upstream from rotor 18.In order to properly align outlet section 14 with portion 20 a, whileisolating inlet section 12 from second portion 20 b, pump 10 includes amovable outlet guide in the form of an outlet swash plate 24 downstreamfrom rotor 18. Inlet swash plate 22 is configured to move to alignportion 20 a of fluid flow space 20 with fluid inlet section 12 andoutlet swash plate 24 is configured to move to align portion 20 b offluid flow space 20 with the fluid outlet section 14. More specifically,swash plates 22 and 24 non-rotatably fixed to rotor 18 such that swashplates 22 and 24 are configured to rotate about center axis 44 in theopposite direction as rotor 18. Swash plates 22 and 24 arecircumferentially offset from each other and on diametrically oppositeradial sides of center axis 44 when viewed cross-sectionally in theaxial direction.

FIG. 24 illustrates an axially facing cross-sectional view stator 16,rotor 18, inlet swash plate 22 and outlet swash plate 24 from the fluidinlet side of pump 10. As shown in FIG. 24 , swash plates 22 and 24 arearranged in a complementary manner to form a circle, with each swashplate 22 or 24 having a semi-circular cross section as define by theouter circumference of each swash plate 22 or 24. Rotor 18 rotates aboutaxis 44 in a rotational direction D3 while swash plates 22 and 24 rotateabout axis 44 in rotational direction D4.

Fluid from the high pressure side, i.e., portion 20 b, is pushed pastoutlet swash plate 24 and out outlet section 14. At the same time, fluidis drawn in through inlet section 12 past inlet swash plate 22, fillingthe vacuum side, i.e., portion 20 a of rotor 18. When rotor 18 istravelling toward a particular winding 26, the next winding 26 isenergized and the process continues, rolling rotor 18 around the insideof stator 16 and pumping fluid from inlet section 12 to outlet section14. Because the high and low pressure sides are continuously movingaround stator 16, swash plates 22 and 24 are used to align the highpressure side with the outlet and the low pressure side with the inlet.Swash plates 22 and 24 are centered on lips 12 a and 12 b of inletsection 12 and lips 14 a and 14 b of outlet section 14, respectively,and are driven by a pin 50 in rotor 18. This causes swash plates 22 and24 to rotate in the opposite direction that rotor 18 is rolling,maintaining alignment with the correct pressures.

As noted above, for an electric reluctance motor, such as is embodied bypump 10, windings 26 energized and de-energized in sequence to createrotating magnetic fields that rotate rotor 18. However, also as notedabove, residual magnetism can remain in stator 16 when a winding 26 isde-energized. Specifically, when an electric current is sent through anyone of windings 26 a magnetic field is created which pulls rotor 18toward that winding 26 in order to complete a magnetic circuit formed bylegs 28 of the stator. Thus, when the particular winding 26 noted aboveis energized, a magnetic field is created through the leg 28 about whichthe particular winding is wrapped. When the next winding 26 isenergized, the particular winding 26 is de-energized. The magnetic fieldcreated by the particular winding 26 is diminished when the particularwinding 26 is de-energized; however, residual magnetism may remain inthe leg 28 about which the particular winding is wrapped. As the nextwinding 26 is energized to rotate the rotor, the residual magnetismresists the rotation of the rotor, interfering with the operation ofpump 10 and reducing the efficiency of pump 10.

However, a circuit 108, wired in parallel with a winding 26 reduces orremoves the residual magnetism from the winding 26. For example, eachwinding 26 is analogous to coil 109 discussed in FIGS. 1 through 4 andeach leg 28 is analogous to ferromagnetic material FM discussed in FIGS.1 through 4 . An attenuating circuit 108 is schematically presented foronly two winding 26 in FIG. 22 . However, it should be understood thatan attenuating circuit can be wired to every winding 26 in pump 10. Anactual configuration and position of circuit(s) 108 is dependent atleast in part upon the configuration of the electrical system poweringwindings 26.

Swash plate 22 and 24 are fixed together and to rotor 18 by pin 50extending axially through rotor 18 and defining center axis 44. Rotor 18is mounted eccentrically on pin 50 such that rotor 18 rotateseccentrically about center axis 44 during operation of pump 10. Inletswash plate 22 is mounted on a first axial end of pin 50 and swash plate24 is mounted on a second axial end of pin 50. Inlet section 12 includesannular groove 52 for guiding the rotation of swash plate 22 and outletsection 14 similarly includes annular groove 54 for guiding the rotationof swash plate 24. The rotation of rotor 18 causes swash plates 22 and24 to slide in annular grooves 52 and 54, respectively, such that theouter circumference of each swash plate 22 or 24 movescircumferentially, but does not move radially, while pin 50 and centeraxis 44 follow a circular path due to the eccentric placement of pin 50on swash plates 22 and 24. Swash plates 22 and 24 each includeconnecting portion 22 a and 24 a and a guide portion 22 b and 24 beccentrically fixed to the respective connecting portion 22 a and 24 a.Guide portions 22 b and 24 b each include a respective outercircumferential surface 22 c and 24 c, a respective longer radiallyextending surface 22 d and 24 d extending radially from the respectiveconnecting portion 22 a and 24 a to a first edge of respective outercircumferential surface 22 c and 24 c and short radially extendingsurface 22 e and 24 e extending radially from the respective connectingportion 22 a and 24 a to a second edge of the respective outercircumferential surface 22 c and 24 c.

Each guide portion 22 b and 24 b also includes an axially protrudingarc-shaped lip 22 f and 24 f configured for sliding in annular grooves52 and 54, respectively. Outer circumferential surfaces 22 c and 24 c oflips 22 f and 24 f slide along outer circumferential surface 52 a and 54a of grooves 52 and 54, respectively, and inner circumferential surfaces22 g and 24 g of lips 22 f and 24 f slide along an inner circumferentialsurface 52 b and 54 b of grooves 52 and 54, respectively. Innercircumferential surface 52 b of annular groove 52 is defined by annularinner circumferential lip 12 a of inlet section 12 and outercircumferential surface 52 a of annular groove 52 is defined by annularouter circumferential lip 12 b of inlet section 12. Similarly, innercircumferential surface 54 b of annular groove 54 is defined by annularinner circumferential lip 14 a of outlet section 14 and outercircumferential surface 54 a of annular groove 54 is defined by anannular outer circumferential lip 14 b of outlet section 14.

Inlet swash plate 22 is axially in contact with a radially extendinginlet side surface 18 a of rotor 18 and an inner portion of a radiallyextending inlet side surface 16 a of stator 16 and outlet swash plate 24is axially in contact with a radially extending outlet side surface 18 bof rotor 18 and an inner portion of a radially extending outlet sidesurface 16 b of stator 16. Annular outer circumferential lip 12 b ofinlet section 12 also contacts radially extending inlet side surface 16a of stator 16 and annular outer circumferential lip 14 b of outletsection 14 contacts radially extending outlet side surface 16 b ofstator 16. Inlet and outlet sections 12 and 14, are provided withflanges 62 and 64, respectively, which in this embodiment aretriangular, that include through holes for receiving fasteners forclamping sections 12 and 14 axially together onto stator 16. Protrudingaxially outward from flanges 62 and 64, respectively, inlet and outletsections 12 and 14 include respective male threaded tubes 68 and 70 forconnecting to corresponding female threaded components.

Pump 10 also includes controller 56 configured to control the flow ofthe current through electrical windings 26 to rotate rotor 18. In anexample embodiment, controller 56 is in the form of transistors on acontrol board for electrically commutating and controlling pump 10.Alternately, the controller can be remote and connected to windings 26by wires.

In the example of FIGS. 20 through 22 , pump 10 is a gerotor pump;however, in other embodiments, a similar construction may be made withother pump types, including an internal gear pump or a vane pump.

It will be appreciated that various of the above-disclosed and otherfeatures and functions, or alternatives thereof, may be desirablycombined into many other different systems or applications. Variouspresently unforeseen or unanticipated alternatives, modifications,variations, or improvements therein may be subsequently made by thoseskilled in the art which are also intended to be encompassed by thefollowing claims.

The following description is made with reference to FIGS. 25 and 26 .FIG. 25 illustrates a perspective view of transmission actuator 400 andtoothed wheel 500. FIG. 26 illustrates a cross-sectional view of thetransmission actuator and toothed wheel of FIG. 25 . Transmissionactuator 400 may be a transmission actuator for a vehicle, for example.The actuator includes fixed actuator housing 402, rocker 404, rotatablein the fixed actuator housing, for engaging toothed wheel 500 to preventrotation of the toothed wheel and a rotatable transmission component(not shown), and rocker 406, rotatable in the fixed actuator housing,for rotating rocker 404 to engage the toothed wheel. As shown in FIG. 26, rocker 404 is rotated away from toothed wheel 500 and is not engagedwith the toothed wheel. But when rocker 406 is rotated counterclockwiseas shown in FIG. 2 and described below, ramped surface 408 pushes tip410 downwards so that engagement portion 412 contacts a tooth 502 of thetoothed wheel to stop rotation of the toothed wheel. When rocker 406 isrotated clockwise, the ramped surface moves away from the tip and rocker404 can rotate up and away from the toothed wheel, via a spring (notshown) or rotation of toothed wheel 500 counterclockwise as shown inFIG. 26 , for example.

Actuator 400 also includes engagement rod 414, linearly displaceablewithin the fixed actuator housing, for rotating rocker 406, and solenoid416 arranged to displace the engagement rod. That is, when the actuatorrod moves to the left in FIG. 26 , rocker 406 is rotatedcounterclockwise to rotate rocker 404 into the toothed wheel, and, whenthe actuator rod moves to the right, rocker 406 is rotated clockwise andaway from rocker 404. Solenoid 416 includes iron core 418, wire coil 420wrapped around the iron core, with a resistance and an inductance asdescribed below, and ferromagnetic plunger 422 disposed radially insidethe wire coil and arranged to linearly displace in direction 424 when afirst directional current is applied to the wire coil and arranged tolinearly displace in direction 426, opposite the direction 424, when asecond directional current, opposite the first directional current, isapplied to the wire coil.

Actuator 400 also includes lost motion spring 428 disposed in a forcepath between the engagement rod and the ferromagnetic plunger. So, forexample, if the plunger is urging the engagement rod in direction 424but rocker 404 is contacting a tooth outer surface, the engagement rodcannot displace so the motion of the plunger is stored as energy in thelost motion spring. Once rocker 404 is aligned with a valley between twoteeth, the engagement rod is displaced by the stored energy in thespring to rotate rocker 406, thereby rotating rocker 404 to engage thetoothed wheel.

The following description is made with reference to FIGS. 25-28 . FIG.27 illustrates a schematic view of electrical circuit 600 for thetransmission actuator of FIG. 25 . FIG. 28 illustrates a schematic viewof electrical circuit 700 for the transmission actuator of FIG. 25 .Actuator 100 also includes solenoid control circuit 600 or 700 arrangedto supply the first directional current when the solenoid controlcircuit is energized by a power source 602/702 and supply a decayingalternating current that includes the first directional current and thesecond directional current when the solenoid control circuit isde-energized from the power source. The wire coil is thereforemagnetized when the solenoid control circuit is energized by the powersource and de-magnetized when the solenoid control circuit isde-energized from the power source.

As shown in FIG. 27 , solenoid control circuit 600 includes capacitor604 connected to opposite ends of the wire coil. Therefore, solenoidcontrol circuit 600 is a passive control circuit that doesn't requireany external controls to operate. By contrast, as shown in FIG. 28 ,solenoid control circuit 700 includes H-bridge circuit 704 andcontroller 706 that controls a direction of a power source current fromthe power source. H-bridge circuit 704 includes actively controlledtransistors 708 that control a direction of current flowing to thesolenoid. In other words, solenoid control circuit 700 is an activecontrol circuit with external controls from controller 706.

The following description is made with reference to FIGS. 25-30 . FIG.29 illustrates a first pair of graphs showing current and magnetismduring a first example engagement and disengagement of the transmissionactuator. FIG. 30 illustrates a second pair of graphs showing currentand magnetism during a second example engagement and disengagement ofthe transmission actuator of FIG. 25 . The present disclosure alsoincludes a method of controlling the transmission actuator includingapplying directional current (ref. 800 in FIGS. 29 and 30 ) from time t0to time t1 with the solenoid control circuit to magnetize the wire coil(ref. 802 in FIGS. 29 and 30 ), charge the capacitor with a capacitorcurrent and displace the ferromagnetic plunger in direction 424 todisplace the engagement rod and engage the rocker 404 with the toothedwheel (ref. FIG. 26 ).

The method also includes reducing the directional current (ref. 804 inFIGS. 29 and 30 ) between times t1 and t2 and holding the directionalcurrent (ref. 806 in FIGS. 29 and 30 ) between times t2 and t3 to holdthe ferromagnetic plunger and keep the first rocker engaged with thetoothed wheel, and removing the first directional current after time t3in FIG. 29 and after t4 in FIG. 30 (ref 808 in FIGS. 29 and 30 ). Asshown in FIG. 30 , for example, the method may also include increasingthe directional current (ref 810 in FIG. 30 ) prior to removing thefirst directional current to increase an inductance in the wire coil.Once the current is removed, a current path is created between thecapacitor and the wire coil and the capacitor discharges through thecoil as shown in portion 812 of the curves in FIGS. 29 and 30 that goesbelow the zero line.

As shown in the graphs, the capacitor current energizes the current pathso that a coil current in the wire coil alternates between the firstdirectional current and the second directional current as the capacitoris charged and discharged. In other words, the current charges the coilwith inductance which is returned to the capacitor with some lossthrough resistor (ref. wire resistance 610 in FIGS. 27 and 710 in FIG.28 ) with each cycle so that, eventually, the current (and the magnetismin the wire coil) falls to zero. In other words, the alternating coilcurrent demagnetizes the wire coil after a time period after a magnetismin the wire coil alternates between a positive value and a negativevalue as the coil current alternates between the first directionalcurrent and the second directional current. Otherwise stated, peakmagnetism 814 approaches zero with each cycle of the alternating coilcurrent.

FIG. 27 shows a diagram of a passive demagnetization embodiment. Acontroller provides a voltage source +Vs and ground to power theactuator solenoid when actuator engagement is desired. Current travelsfrom the controller to the solenoid and back through wire withresistance R1 and R2. The solenoid itself has resistance Rc andinductance Lc. A parallel capacitor is added across the solenoid withcapacitance C1.

The value of C1 is chosen such that when controller power is removedfrom the coil, a resonant LRC circuit is established in the loop betweenthe coil and the parallel capacitor. When power is removed, anoscillating and continuously decreasing current occurs in the loop. Thishas the effect of repeatedly reversing the magnetic domains in thesolenoid material, which works to eventually randomize them in a waythat any residual field is brought to near zero.

FIG. 29 shows the current and magnetic field response versus time for asimple implementation of the passive demagnetization system. From timet0 to t3 the behavior is unchanged from a system without passivedemagnetization. At time t3 the controller commands that the actuatordisengages, and the applied voltage is removed. Because of the resonantLRC circuit, a current oscillation through the solenoid occurs,decreasing as energy is lost through the coil resistance Rc. This causesan inwardly spiraling B-H characteristic and the B field eventuallyreaches near zero strength at time tf.

It is possible that the energy stored in the inductor subject to holdingcurrent Ih is insufficient to provide enough randomizing oscillations,and so the passive method shown in FIG. 29 might not fully eliminate theresidual field Br. FIG. 30 shows a different implementation whichaddresses this. From time t0 to t3, the behavior is unchanged from FIG.29 . At time t3, instead of removing the applied voltage, the controllerbriefly increases the commanded current from Ih back up to Is to fullycharge the inductor with more magnetic potential energy. The appliedvoltage is then turned off at t4, and again an inwardly spiraling B-Hcurve occurs. This time, the oscillations are more aggressive (and morewaves are able to occur before all energy is lost in the coilresistance) so the magnetic domains are more thoroughly randomized.

FIG. 28 shows the active implementation of this strategy. In this case,the controller interfaces with an H-bridge instead of adding theparallel capacitor across the solenoid. The controller has outputs tocontrol the MOSFET's in the H-bridge, allowing for either forward orreverse current to be applied. This gives full control over the currentwaveform in the solenoid, and so, with software, any demagnetizationroutine can be run. Therefore, this embodiment does not requireselecting a capacitor such that the desired oscillation is produced;instead the oscillation is simply commanded. Though this method is themost flexible (and least sensitive to temperature changes), it involvesadded complexity in running due to the H-bridge.

While exemplary embodiments are described above, it is not intended thatthese embodiments describe all possible forms encompassed by the claims.The words used in the specification are words of description rather thanlimitation, and it is understood that various changes can be madewithout departing from the spirit and scope of the disclosure. Aspreviously described, the features of various embodiments can becombined to form further embodiments of the disclosure that may not beexplicitly described or illustrated. While various embodiments couldhave been described as providing advantages or being preferred overother embodiments or prior art implementations with respect to one ormore desired characteristics, those of ordinary skill in the artrecognize that one or more features or characteristics can becompromised to achieve desired overall system attributes, which dependon the specific application and implementation. These attributes caninclude, but are not limited to cost, strength, durability, life cyclecost, marketability, appearance, packaging, size, serviceability,weight, manufacturability, ease of assembly, etc. As such, to the extentany embodiments are described as less desirable than other embodimentsor prior art implementations with respect to one or morecharacteristics, these embodiments are not outside the scope of thedisclosure and can be desirable for particular applications.

REFERENCE NUMERALS

-   -   AR axis of rotation    -   B magnetic flux density    -   B_sat saturation point    -   B_r residual magnetism    -   CU control unit    -   CV1 control voltage    -   CV2 control voltage    -   D1 direction    -   D2 direction    -   D3 direction    -   D4 direction    -   EC1 electrical current    -   EC2 electrical current    -   EG electrical ground    -   EPS electrical power source    -   FM ferromagnetic material    -   G1 gate    -   G2 gate    -   G3 gate    -   H magnetic field strength    -   MF magnetic field    -   OC oscillating circuit    -   OW oscillating waveform    -   R resistor value    -   R1 resistor    -   RIC radially inner circumference    -   ROC radially outer circumference    -   SL1 slot    -   SL2 slot    -   Vc capacitor voltage    -   Vs source voltage    -   10 pump    -   12 fluid inlet    -   12 a lip, fluid inlet    -   12 b lip, fluid inlet    -   14 fluid outlet    -   14 a lip, fluid inlet    -   14 b lip, fluid inlet    -   16 stator    -   16 a surface, stator    -   16 b surface, stator    -   18 rotor    -   18 a surface, rotor    -   18 b surface, rotor    -   20 fluid flow space    -   20 a portion, fluid flow space    -   20 b portion, fluid flow space    -   22 inlet guide    -   22 a portion, inlet guide    -   22 b portion, inlet guide    -   22 c portion, inlet guide    -   22 d portion, inlet guide    -   22 e portion, inlet guide    -   22 f portion, inlet guide    -   22 g portion, inlet guide    -   24 outlet guide    -   24 a portion, outlet guide    -   24 b portion, outlet guide    -   24 c portion, outlet guide    -   24 d portion, outlet guide    -   24 e portion, outlet guide    -   24 f portion, outlet guide    -   24 g portion, outlet guid    -   26 windings    -   28 leg, stator    -   30 ring, stator    -   32 base, leg    -   34 branches, leg    -   36 tip, leg    -   38 protrusion    -   40 tip    -   42 slot    -   44 center axis    -   50 pin    -   52 groove, inlet section    -   52 a surface groove, inlet section    -   52 b surface groove, inlet section    -   54 groove, outlet section    -   54 a surface groove, outlet section    -   54 b surface groove, outlet section    -   56 controller    -   62 flange, inlet    -   64 flange, outlet    -   68 tube    -   70 tube    -   100 wedge plate clutch    -   102 outer race    -   104 inner race    -   105 end, coil core piece    -   105A end, coil core piece    -   105B end, coil core piece    -   106 wedge plate    -   106A wedge plate    -   106B wedge plate    -   106C wedge plate    -   106D wedge plate    -   106E wedge plate    -   106F wedge plate    -   107 electromagnetic actuator    -   107A electromagnetic actuator    -   107B electromagnetic actuator    -   107C electromagnetic actuator    -   108 attenuating circuit    -   109 coil    -   110 coil core piece    -   110A coil core piece    -   110B coil core piece    -   111 end, coil core piece    -   111A end, coil core piece    -   111B end, coil core piece    -   112 capacitor    -   113 switch, transistor    -   114 switch, transistor    -   115 transistor    -   116 bobbin    -   118 air gap    -   120 circumferential end, wedge plate    -   122 circumferential end, wedge plate    -   124 gap    -   126 circumferential end, wedge plate    -   128 circumferential end, wedge plate    -   130 gap, wedge plate    -   132 bolt    -   134 ramp, wedge plate    -   136 ramp, wedge plate    -   138 ramp, inner race    -   140 inner race    -   142 bolt    -   144 circumferential end, wedge plate    -   146 circumferential end, wedge plate    -   148 gap, wedge plate    -   150 circumferential end, wedge plate    -   152 circumferential end, wedge plate    -   154 gap, wedge plate    -   156 ramp, wedge plate    -   158 ramp, wedge plate    -   160 ramp, inner race    -   162 chamfer    -   164 chamfer    -   166 groove    -   168 chamfer    -   170 chamfer    -   172 groove    -   174 slot    -   176 slot    -   178 slip ring retainer    -   180 slip ring    -   220 wedge clutch    -   222 outer race    -   224 inner race    -   226 circumferential end, wedge plate    -   228 circumferential end, wedge plate    -   230 gap, wedge plate    -   232 circumferential end, wedge plate    -   234 circumferential end, wedge plate    -   236 gap, wedge plate    -   237 bolt    -   238 ramp, wedge plate    -   239 ramp, wedge plate    -   240 ramp, wedge plate    -   241 ramp, wedge plate    -   242 ramp, inner race    -   243 ramp, inner race    -   244 chamfer    -   246 chamfer    -   248 groove    -   250 slot    -   252 slip ring retainer    -   254 slip ring    -   300 electromagnetic actuator    -   302 outer race    -   304 inner race    -   306 wedge plate    -   308 electromagnetic actuator    -   310 coil    -   312 coil core piece    -   314 end, coil core piece    -   316 end, coil core piece    -   318 finger, wedge plate    -   400 Transmission actuator    -   402 Fixed actuator housing    -   404 Rocker (first)    -   406 Rocker (second)    -   408 Ramped surface    -   410 Tip    -   412 Engagement portion    -   414 Engagement rod    -   416 Solenoid    -   418 Iron core    -   420 Wire coil    -   422 Ferromagnetic plunger    -   424 Direction (first so t, e)    -   426 Direction (second)    -   500 Toothed wheel    -   502 Tooth    -   600 Electrical circuit (first)    -   602 Power source    -   604 Capacitor    -   610 Wire resistance    -   700 Electrical circuit (second)    -   702 Power source    -   704 H-bridge circuit    -   706 Controller    -   708 Transistors    -   710 Wire resistance    -   800 Applying directional current    -   802 Magnetizing wire coil    -   804 Reducing directional current    -   806 Maintaining directional current    -   808 Removing directional current    -   810 Increasing directional current    -   812 Capacitor discharge current    -   814 Peak magnetism

1. A transmission actuator for a vehicle, comprising: a fixed actuatorhousing; a first rocker, rotatable in the fixed actuator housing, forengaging a toothed wheel to prevent rotation of the toothed wheel and arotatable transmission component; a second rocker, rotatable in thefixed actuator housing, for rotating the first rocker to engage thetoothed wheel; an engagement rod, linearly displaceable within the fixedactuator housing, for rotating the second rocker; a solenoid arranged todisplace the engagement rod, the solenoid comprising: an iron core; awire coil wrapped around the iron core, the wire coil having aresistance and an inductance; and a ferromagnetic plunger disposedradially inside the wire coil and arranged to linearly displace in afirst direction when a first directional current is applied to the wirecoil and arranged to linearly displace in a second direction, oppositethe first direction, when a second directional current, opposite thefirst directional current, is applied to the wire coil; and a solenoidcontrol circuit arranged to: supply the first directional current whenthe solenoid control circuit is energized by a power source; and supplya decaying alternating current that includes the first directionalcurrent and the second directional current when the solenoid controlcircuit is de-energized from the power source.
 2. The transmissionactuator of claim 1 further comprising a lost motion spring disposed ina force path between the engagement rod and the ferromagnetic plunger.3. The transmission actuator of claim 1 wherein the wire coil is:magnetized when the solenoid control circuit is energized by the powersource; and de-magnetized when the solenoid control circuit isde-energized from the power source.
 4. The transmission actuator ofclaim 1 wherein the solenoid control circuit includes a capacitorconnected to opposite ends of the wire coil.
 5. The transmissionactuator of claim 4 wherein the solenoid control circuit is a passivecontrol circuit.
 6. The transmission actuator of claim 1 wherein thesolenoid control circuit includes: an H-bridge circuit; and a controllerthat controls a direction of a power source current from the powersource.
 7. The transmission actuator of claim 6 wherein the solenoidcontrol circuit is an active control circuit.
 8. A method of controllingthe transmission actuator of claim 4 comprising: applying the firstdirectional current with the solenoid control circuit to: magnetize thewire coil; charge the capacitor with a capacitor current; and displacethe ferromagnetic plunger in the first direction to displace theengagement rod and engage the first rocker with the toothed wheel;reducing the first directional current to hold the ferromagnetic plungerand keep the first rocker engaged with the toothed wheel; and removingthe first directional current.
 9. The method of claim 8 furthercomprising increasing the first directional current prior to removingthe first directional current.
 10. The method of claim 9 wherein thestep of increasing the first directional current increases an inductancein the wire coil.
 11. The method of claim 8 wherein, after the step ofremoving the first directional current, a current path is createdbetween the capacitor and the wire coil.
 12. The method of claim 11wherein the capacitor current energizes the current path so that a coilcurrent in the wire coil alternates between the first directionalcurrent and the second directional current as the capacitor is chargedand discharged.
 13. The method of claim 12 wherein the alternating coilcurrent demagnetizes the wire coil after a time period.
 14. The methodof claim 12 wherein a magnetism in the wire coil alternates between apositive value and a negative value as the coil current alternatesbetween the first directional current and the second directionalcurrent.
 15. The method of claim 14 wherein a peak magnetism approacheszero with each cycle of the alternating coil current.
 16. A transmissionactuator for a vehicle, comprising: a solenoid comprising: an iron core;a wire coil wrapped around the iron core, the wire coil having aresistance and an inductance; a capacitor connected to opposite ends ofthe wire coil; and a ferromagnetic plunger disposed radially inside thewire coil and arranged to linearly displace in a first direction when afirst directional current is applied to the wire coil and arranged tolinearly displace in a second direction, opposite the first direction,when a second directional current, opposite the first directionalcurrent, is applied to the wire coil; and a solenoid control circuitarranged to: supply the first directional current when the solenoidcontrol circuit is energized by a power source; and supply a decayingalternating current that includes the first directional current and thesecond directional current when the solenoid control circuit isde-energized from the power source.
 17. A method of controlling thetransmission actuator of claim 16 comprising: applying the firstdirectional current with the solenoid control circuit to: magnetize thewire coil; charge the capacitor with a capacitor current; and displacethe ferromagnetic plunger in the first direction; reducing the firstdirectional current to hold the ferromagnetic plunger; and removing thefirst directional current.
 18. The method of claim 17 further comprisingincreasing the first directional current to increase an inductance inthe wire coil prior to removing the first directional current.
 19. Themethod of claim 17 wherein, after the step of removing the firstdirectional current, the capacitor current energizes a current pathbetween the capacitor and the wire coil so that a coil current in thewire coil alternates between the first directional current and thesecond directional current as the capacitor is charged and discharged,demagnetizing the wire coil after a time period.
 20. The method of claim19 wherein: a magnetism in the wire coil alternates between a positivevalue and a negative value as the coil current alternates between thefirst directional current and the second directional current; and a peakmagnetism in the wire coil approaches zero with each cycle of thealternating coil current.